This invention pertains to aqueous polymeric compositions and, more particularly, to an additive and vehicle system for water based printing inks, paints, coatings and adhesives.
It is important to minimize, if not eliminate, volatile organic compound (VOCs) from paints, printing inks, coatings, and adhesives. Fumes emitted from such materials can be hazardous to the health and well-being of workers in paint manufacturing plants, printing companies, coating shops, and adhesive facilities. These fumes can be caused by flashing and vaporizing of solvents and free monomers. Furthermore, prolonged exposure to volatile emissions can impair the sight or brain function, and internal organs of people exposed to the volatile emissions. Some VOCs are also carcinogenic. It is often recommended that consumers using paints, printing inks, coatings, adhesives, and like materials, do so outside or in a well ventilated area to decrease health risks and injury. This is not always possible, particularly in wintertime or if the work is going to be done outside.
Not only can VOCs be injurious to the health and welfare of society, but specific amounts of VOCs are often prohibited or controlled by environmental laws. Moreover, products containing VOCs often cause waste disposal problems and expensive cleanup costs to comply with local anti-dumping ordinances and environmental regulations.
It is also desirable that printing inks, coatings, paints, and adhesives can be rapidly transferred, dispersed, dispensed, spread, and dried to increase throughput and production. This is especially important for four color printing on Gravure presses. Multiple color printing should have enough tack with yellow pigments to trap and avoid splattering of red pigments and subsequent dispersants. Furthermore, it is desirable that vehicles or carriers for printing inks, to coatings, paints and adhesives be rewettable or resolubilize so they do not stick to, gum up or clog printing presses and production equipment causing undesired downtime, decreased output, repairs and expense. Many conventional printing inks, paints, coatings, and adhesives become unstable during storage, which can lead to phase separation, layering, loss of quality, and delamination of the product.
Latex-based ink technology developed by Robert Slocombe is disclosed in U.S. Pat. Nos. 4,374,670 and 4,414,354. The Slocombe technology provided an approach which promised to solve some basic problems associated with waterborne inks and coatings. Among the promised benefits of the Slocombe technology were adhesion to low energy surfaces, high speed printing, and the ability to disperse most pigments.
The promise of the Slocombe technology was never realized for a number of reasons. The Slocombe technology centers around the high degree of free monomers which are present in Slocombe's product. The Slocombe technology is also limited to rubber-based resins. Slocombe's technology further needed to be activated by ultraviolet radiation which was not previously available. Slocombe's three component system had a limited pot life once the components were mixed together. Slocombe's inks further require a cosolvent to incorporate an initiator, polyelectrolyte and latex into a miscible solution. Moreover, Slocombe's cosolvents were unstable volatile organic solvents which are undesirable from an environmental viewpoint. Slocombe's polyelectrolyte interaction was also inefficient, and often amounted to 15%-25% of the resin formulation. These expensive compounds often resulted in inks which were too costly to be economically viable.
It is therefore desirable to provide an improved vehicle system for use in water-based printing inks, paints, coatings and adhesives, which avoids substantial use of solvents and volatile organic compounds, and overcomes most, if not all, of the preceding problems.